Fiber optic scopes permit visualization of the interior of various cavities in human and veterinary medicine applications. The scopes are delicate, costly devices that are typically exposed to body fluids during diagnostic or therapeutic medical procedures. When exposed to body fluids, scopes are potentially damaged by corrosive or abrasive action. Scopes also become contaminated with pathogens such as bacteria, fungi, parasites, and viruses. These pathogens can be transmitted to another patient during a subsequent procedure. The possibility of introducing an infection with an endoscope positioned in a lung, bladder, or kidney, for example, seriously impacts a generally healthy patient; however, the impact is more severe on an immuno-compromised patient such as one suffering from AIDS or following an immuno-suppression drug regimen.
The problem of contaminated scopes has previously been managed by cleaning and disinfecting a scope after each clinical use. First, the scope is mechanically cleaned with solutions to remove debris and organic matter that may be accumulated thereon or therein. The scope is then soaked in a disinfecting solution such as glutaraldehyde for at least 25 minutes, depending on the type of scope. Finally, the scope is rinsed and dried to remove all disinfectant. Special care must be taken to ensure that no traces of the toxic disinfecting solution remain on the scope, since a patient can be harmed by exposure to toxic traces. The scope also must be specially stored between clinical uses to prevent contamination after cleaning. The cleaning and disinfecting procedures are labor intensive, time consuming, and require significant handling of a scope, which can shorten the life of a scope. The chemicals used to clean and disinfect a scope can also cause deterioration to the scope, as well as cause significant health hazards to medical personnel cleaning the scope. Furthermore, some reports indicate that these cleaning and disinfecting procedures are not always effective, probably due to incomplete contaminant removal. Even when the cleaning and disinfecting procedures are successful, the best possible result is a scope that is surgically clean, not sterile.
One attempt to solve the above-mentioned problems is to use a disposable sheath that is positioned about the exterior surface of a scope for minimizing contact of the scope with body fluids. Known scope sheaths are generally formed from an elastic material tube with a closed, transparent distal end. A problem with the use of elastic material scope sheaths is that they snugly adhere to the exterior wall of the scope. As a result, the elastic material of the sheath resists deformation when the scope is bent or flexed. Therefore, the sheath is formed from a very thin piece of elastic material. Another problem with the use of thin-walled, elastic material scope sheaths is that the material is readily torn when engaging anatomical surfaces such as the teeth during a bronchoscopy or gastroscopy procedure. As a result, the scope becomes contaminated and possibly damaged due to exposure to body fluids.
Yet another problem with the use of elastic material scope sheaths is that they fit tightly around an endoscope with a high coefficient of friction. As a result, it is difficult to position a scope therein. A machine is typically used for either inflating or distending a sheath by creating a vacuum around the outside of the sheath in order to position a scope inside the sheath. The process of inflating or distending a sheath is inconvenient and costly in terms of time and equipment.
Still yet another problem with the use of elastic material scope sheaths is that the closed, transparent distal end of a sheath is typically rigid and thick. As a result, the distal end tends to behave as a lens and obstruct or distort visualization therethrough.